Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cellular and Molecular Biology > Lecture 28: Energy and Metabolism (2) > Flashcards

Lecture 28: Energy and Metabolism (2) Flashcards

Wednesday 20th November 2024

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Is it true that ΔG tells us whether a reaction will happen or not?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Glucose-6-phosphate Fructose-6-phosphate

Is this the 2nd reaction of glycolysis?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Glucose-6-phosphate Fructose-6-phosphate

Is this reaction close to equlibrium?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Glucose-6-phosphate >< Fructose-6-phosphate

When this reaction is at equilibrium, what will ΔG be?

A
  1. This will only be for a very short period of time and there will be no overall change as G-6-P and F-6-P will be interconverted with equal rate in both directions.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Glucose-6-phosphate >< Fructose-6-phosphate

What happens when more [G-6-P ] is added?

A
  • An increase in the formation of F-6-P
  • ΔG is negative
  • Reaction will occur spontaneously, this is the 2nd reaction of glycolysis

-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Glucose-6-phosphate >< Fructose-6-phosphate

What happens when more [F-6-P ] is added?

A
  • An increase in the formation of G-6-P
  • ΔG is positive
  • This happens during gluconeogenesis (metabolic process that synthesises glucose)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Is ΔG dependant on concentration?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Glucose-6-phosphate Fructose-6-phosphate

Does the same enzyme catalyse both the forwards and backwards reaction?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the first step of glycolysis?

A

Glucose + ATP Glucose-6-phosphate + ADP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Glucose + ATP Glucose-6-phosphate + ADP

Does this reaction have a large ΔG?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Glucose + ATP Glucose-6-phosphate + ADP

In a living cell, does this reaction happen quite far away from equlibrium?

A

Yes. So ΔG &laquo_space;0 and under physiological conditions this means irreversible
.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Is it true that the further away from equilibrium, the larger the value of ΔG?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is q?

A

The mass action ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the equation for the mass action ratio?

A

A + B C + D

Mass action ratio: q = [C] [D]/
[A] [B]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

F-1,6-bP G3P + DHP

Put this equation into the mass action ratio

A

q = [G3P] [DHP] / [F-1,6-bP]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

If there’s a lot of product in the system, how large will q be?

A

Very large

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Effectively, what is the mass action ratio an expression of?

A

How much product in system vs how much reactant in system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

If there’s a lot of reactant in the system, how large will q be?

A

Very small

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does the mass action ratio allow us to measure?

A

how far we are from equilibrium conditions. At equilibrium q = Kp (equilibrium constant)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the standard free energy equation?

A

ΔG = ΔG0 +RT lnq

(units J/mol or kcal/mol
R: gas constant
T: absolute temperature
q: mass action ratio
ΔG0: Standard Free Energy )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is ΔG0?

A

The standard free energy, which is the change in Free Energy when concentration of all reactants and products are 1M at 25oC, 1 atm. (standard conditions)

Tells you if a reaction tends towards the products side or towards the reactants side

Artificial reference point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is our definition of Standard free energy ,ΔG0’?

A

Standard Free Energy at pH 7 at 25oC and 1 atm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is ΔG dependant on?

A

The nature of a reaction (whether a reaction tends to the reactant or the product side) AND the concentrations (q from mass action ratio)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

If ΔG = 0….

A

… no free energy change takes place and the system is at equilibrium

(rate of degradation = rate of formation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Is the standard free energy just another way of expressing the equilibrium constant?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

When ΔG0’ is 0, what is q?

A

The equilbrium constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

q = [C][D] / [A][B] = Keq at equilibrium

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Does the equilibrium constant tell you whether or not a reaction tends to the reactants or products side?

A

Yes (standard free energy is another way of expressing this, also dependant on one another)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What can the relationship between ΔG0’ and Keq be described as?

A

Logarithmic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Is it true that Relatively small changes in ΔG0’ can lead to big changes in Keq?

A

Yes

31
Q

How many phosphates does ATP have?

A

3

32
Q

How many phosphates does ADP have?

A

2

33
Q

How many phosphates does AMP have?

A

1

34
Q

Draw out the structure of ATP

A
35
Q

Draw out the structure of ADP

A
36
Q

Draw out the structure of AMP

A
37
Q

ATP + H2O ADP + Pi

What is ΔG0’ for this reaction?

A

– 30.5 kJ/mol

38
Q

ADP + Pi ATP + H2O

What is ΔG0’ for this reaction?

A

ΔG0’ = 30.5 kJ/mol

39
Q

TP + H2O AMP + PPi

What is ΔG0’ for this reaction?

A

ΔG0’ = – 45.6 kJ/mol

40
Q

Why do we usually talk about ATP and ADP, but not AMP?

A

Because AMP is rapidly converted back to ADP via the adenylate kinase reaction: 2ADP↔ATP+AMP. This ensures AMP does not accumulate significantly in cells, further reducing its direct biochemical relevance.

41
Q

Generally, are most reactions in the body at equilibrium ?

A

No

42
Q

Does ATP have high energy bond compared to other bonds?

A
  • No, this is a myth
  • Instead, ΔG0’ is very negative and this favours the product formation
  • The energy is the potential energy stored in being far from equilibrium i.e. q«KD (lots of reactants, not much of products compared to equilibrium conditions)
43
Q

What are the roles of ATP?

A

-

44
Q

Which 2 ways can ATP be made?

A

From photosynthesis and from respiration

45
Q

Is it true that ATP and ADP are always interconverting between one another?

A

Yes

46
Q

How much ATP do humans need a day?

A

About 70kg

47
Q

Can Keq be affected by coupling reactions?

A

Yes

48
Q

Glucose + Pi Glucose-6-phosphate + H2O ΔGo’ = + 14.0 kJ/mol; Keq = 3.5 x10-3

ATP + H2O ADP + Pi ΔGo’ = - 30.5 kJ/mol

Glucose + ATP Glucose-6-phosphate + ADP ΔGo’ = - 16.5 kJ/mol; Keq = 8.0 x 102

A

By coupling to ATP the equilibrium has been shifted 5 orders of magnitude
(N.B! not this only works because Pi is a shared intermediate
) (created a reaction that will occur under physiological conditions)

49
Q

Are redox reactions used for storing and releasing energy?

A

Yes

50
Q

What happens to glucose during glycolysis?

A

It’s oxidised

51
Q

Glucose is oxidised during glycolysis. What is the potential energy from this redox reaction used to do?

A

The potential energy from this redox reaction is used to generate ATP

52
Q

What happens to Acetyl-CoA in the citric acid cycle?

A

It is oxidised

53
Q

Acetyl-CoA is oxidised in citric acid cycle. What is the potential energy from this redox reaction used to do

A

Used to generate reduced NADH/ FADH2
i.e., potential energy is stored in redox reaction

54
Q

What happens to NADH/ FADH2 in oxidative phosphorylation?

A

They’re oxidised.

55
Q

NADH/ FADH2 are oxidised in oxidative phosphorylation. What is the potential energy from this redox reaction used to do?

A

The potential energy from this redox reaction is used to generate ATP.

56
Q

What do redox reactions involve?

A

The transfer of electrons

57
Q

What happens during oxidation reactions?

A

A compound donates electrons

58
Q

What happens during reduction reactions?

A

A compound accepts electrons

59
Q

NADH + ½ O2 H2O + NAD+

Half equations
½ O2+ 2H+ +2e- H2O
NADH NAD+ + 2H+ + 2e-

A
60
Q

What is the redox potential?

A

How many electrons around before the compound will become reduced (accept electrons)?

61
Q

What is ΔE0’ ?

A

The standard biochemical redox potential

62
Q

What does a good oxidising agent do?

A

Takes up electrons, even when there are not many around

63
Q

what does a good reducing agent do ?

A

Gives off electrons, even when there’s many around

64
Q

What equation links free energy to redox potentials?

A

ΔG0’ = -nFΔE0’,

Where n = number of electrons and F = faraday constant 96.48 kJ V-1mol-1

Under standard conditions, A positive ΔE0’ gives a negative ΔG0’

65
Q

Is gibbs free energy available to do work?

A

Yes

66
Q

Does Gibbs free energy tell us whether a reaction is spontaneous or not?

A

Yes

67
Q

What is Gibbs free energy dependant on?

A

on enthalpy (related to total energy) and entropy (disorder)

68
Q

What is free energy dependant on?

A

the nature of a reaction (standard Gibbs free energy) and the concentrations (mass action ratio)

69
Q

What is the standard free energy defined as?

A

all concentrations 1 M, 250C and 1 atm or in biology at pH 7

70
Q

IS it true that at equilibrium, the mass action ratio is the equilibrium constant?

A

Yes

71
Q

‘ATP is the main energy carrier and energy ”harvested” as ATP can be used to run endergonic reactions’. Is this statement true?

A

Yes

72
Q

‘The redox potential describes a compounds propensity to accept or donate electrons and is related to the standard free energy’. Is this statement true?

A

Yes

73
Q
A

Cellular and Molecular Biology (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions